Work

Ablation of Twin Atrioventricular Node‐Mediated Macroreentrant Tachycardia in a Patient With Complex Heterotaxy Syndrome

Year: 2026

Type: article

Abstract: Twin atrioventricular (AV) nodes constitute a rare and highly complex electrophysiological substrate for tachycardia in heterotaxy syndrome (complex cardiac heart disease). We present the case of an 18-year-old male with right atrial isomerism, asplenia, univentricular physiology, and a Glenn shunt, who presented with a regular wide-QRS tachycardia associated with severe hemodynamic decompensation. High-density electroanatomical mapping identified two distinct His bundle recordings separated by 20.3 mm. Together with two non-preexcited QRS morphologies and different conduction properties, these findings supported suspected twin AV node-mediated macroreentry, with proposed anterograde conduction via the inferior-posterior system and retrograde conduction through the superior-anterior system; complete circuit mapping and entrainment were not possible. Following an initial procedure complicated by pulseless electrical activity clinically attributed to post-cardioversion myocardial stunning, a second electrophysiological study prioritized functional characterization during sinus rhythm and atrial pacing without preablation reinduction of the clinical tachycardia. Selective ablation of the superior-anterior His region preserved AV conduction and was followed by noninducibility of the clinical tachycardia. A separate isthmus-dependent flutter was also ablated. At two months, clinical assessment, ECG, and 24-hour Holter monitoring showed no documented recurrence or new AV block.

Source: Pacing and Clinical Electrophysiology

DOI: 10.1111/pace.70497